The instant invention is directed to a coil link dryer fabric in which stuffers are inserted into open areas to reduce the porosity of the dryer fabric.
In general, dryer fabrics of this structure are known. U.S. Pat. Nos. 4,490,925 and 5,364,692 are two such structures in which the porosity or permeability has been reduced from about 900 CFM to about 450 CFM. These fabric structures are not completely satisfactory due to uneven porosity created when in use in the dryer section.
In FIG. 1 there is shown a schematic sectional drawing of a dryer fabric A carrying a sheet of paper forming fibers B through a dryer section of a paper forming machine. As dryer fabric A passes first over and then beneath heated rolls C and D fluid is removed from fibers B and passes through the dryer fabric. It has been found that as the dryer fabric passes beneath heated rolls D, the rolls assist in holding fibers B smoothly and firmly against the dryer fabric as is desired. However, when passing over heating rolls C a certain amount of air is pushed upward from rolls C through the paper forming fibers. Should passage of this air be uneven due to uneven porosity of the dryer fabric or due to uneven air pockets having been formed, there is a danger of certain ones of the fibers being separated from the dryer fabric causing uneven drying and in some cases creases in the fiber sheet.
To this end, it is an object of the invention to provide a coil link dryer fabric of reduced and even porosity.
Another object of the invention is to provide a coil link dryer fabric with a shaped stuffer filling selected areas of the inner space of the coils.
Another object of the invention is to provide a dryer fabric of coil link construction which controls its permeability more evenly during the drying operation.
Another object of the invention is the provision of a heat set coil link dryer fabric of uniform stability and porosity.